Warm inflationary scenario in modified teleparallel gravity with matter-torsion coupling

Abstract

This study investigates warm inflation in the context of modified teleparallel gravity specifically $f(T,T)$ gravity under strong dissipative conditions ($r>1$). We examine two inflationary potentials, Chaotic and Natural, evaluating scenarios with both constant and variable dissipation coefficients. For the Chaotic potential with a fixed dissipation parameter, the spectral index shows negligible sensitivity to the model’s parameters, while the tensor-to-scalar ratio depends markedly on them. Notably, certain choices for the potential exponent align well with Planck 2018 observational data. When the dissipation coefficient becomes variable, only one specialized case of the Chaotic potential remains consistent with observational limits. Here, shifts in model parameters dynamically adjust the relevant energy scales. Turning to the Natural potential, our analysis reveals that $f(T,T)$ gravity corrections prove pivotal: they not only reshape the spectral index and tensor-to-scalar ratio but also allow the spontaneous symmetry breaking scale to dip below the Planck scale while still matching experimental constraints. These outcomes sharply contrast with cold inflation models, where analogous $f(R,T)$ gravity modifications fail to salvage such potentials. Ultimately, we suggest that probing alternative $f(T,T)$ functional forms and reevaluating other previously excluded potentials could deepen our understanding of warm inflation’s feasibility.